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We all have indispensible tools we use in science. A sturdy bucket for sampling intertidal critters and seaweeds. Our trusty calipers for measuring morphometrics. Our favorite R-package for numerical ecology. All these are important for doing science. My favorite tool for scientific communication and outreach are pretty photos! A good photo can captivate and create interest in your work and, more importantly, let you communicate science to a much greater audience.

As a graduate student living on mac and cheese, I cobbled together my used camera equipment from various online sources (e.g. eBay). The camera brand really makes no difference. I would estimate I spent ~$300 for everything: $200 for the camera, $50 for the lens, $2 for the reversing ring, and $50 for the flash. Because I am always working with small (but not microscopic) invertebrates, one trick to close-up (macro) photography is to mount the lens backwards onto the camera using the reversing ring. A 50mm lens mounted backwards onto a camera will give you a 1:1 magnification ratio (1 cm object will be 1 cm on the camera sensor). A backwards mounted 28 mm lens will give you a higher magnification ratio of 3:1. There are also other alternatives that yield similar results: macro-focusing teleconverters, extension tubes, or dedicated macro lenses. In order to get proper lighting, a flash will have to be oriented close to the object. You can do this in one of two ways. Modern day flashes can be wirelessly triggered from the camera. Otherwise, an off-camera flash cord can be used.

Most of the time I’m trying to take photos of my live study organisms. What’s worked for me is to use a shallow, flat-bottomed glass tray filled with filtered seawater. Petri dishes work great for tiny 1-cm critters like carnivorous sponges. Glass baking dishes are great for >5 cm sized critters like nudibranchs and seapigs. I usually slip my neoprene laptop sleeve underneath the tray of seawater to create a black background in my photos.

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We are used to seeing crabs scuttling across the seafloor or scrambling under rocks in the intertidal zone, but before they settle on the seabed they have larval stages that live in the water column as plankton. Zoeae (pronounced zoe-EE-uh) and megalopae (MEG-uh-lope-ee) drift through the water, eating food and eventually metamorphosing into bottom-dwelling crabs.

Life cycle stages of a crab: an egg hatches into swimming zoea stages, then to a megalopa, then metamorphoses into a benthic juvenile and adult crab. Image credit: A Snail’s Odyssey

For her class project in Crustacean Biology (a summer course taught in 2012), Anna Smith worked with instructor Greg Jensen to study how swimming is accomplished by the zoeae of a porcelain crab, Petrolisthes cinctipes. Most crab larvae swim vertically in the water column and are fairly poor swimmers. These zoeae are swept along with the currents and are often taken out to sea with no hope of returning to the shore to settle. Check out the video below to see how zoeae of most crab species move in the water.

Most crab zoeae have sharply pointed spines projecting from their carapace, as pictured below. Previous studies have found these spines to be connected with predator avoidance by making the larvae harder to swallow. The zoeae of porcelain crabs, however, have unusually long spines sticking out the front and back of the carapace. They are also much stronger swimmers than zoeae of many crab species, enabling them to stay close to shore and avoid being swept away from settling grounds. These zoeae swim horizontally through the water column and exhibit much more directional control than most crab zoeae. Anna studied whether the elongated spines of porcelain crabs were connected to their unique swimming by studying their swimming ability with both spines intact, then removed the front, back, or all spines to see how their swimming changed.

The spines were in fact very important to the swimming ability of the zoeae. Zoeae who had their front (anterior) spine removed could not maintain constant depth in the water. Zoeae who had their posterior spines removed could not swim backwards or change directions easily and with both front and back spines removed the zoeae could not swim at all. This led Anna and Greg to conclude that the spines contribute to the superior swimming ability of porcelain crab zoeae.

Why is this important? This suggests that the carapace spines are not only used as physical protection from predators, as previously suggested, but also contribute to their survival in other ways. Anna and Greg also hypothesize that the ability to better control direction and water column depth helps the zoeae navigate currents and stay close to shore and may explain their limited dispersal offshore.

Citation:

Smith, AE, and GC Jensen (2015). The role of carapace spines in the swimming behavior of porcelain crab zoeae (Crustacea: Decapoda: Porcellanidae). Journal of Experimental Marine Biology and Ecology, 471:175-179.

Sponges are animals, but they do not have the features we’re used to seeing when we think of animals: no gut, no head or tail, no nerves, and no stomachs or other organs. And yet despite not having a nervous system, sponges are able to respond to their environment by changing the canal sizes in their filter-feeding system, in an action called the “inflation-contraction response.” It’s basically akin to what we do when we sneeze. This was observed in the mid-1900’s, but scientists have only been able to speculate what could be helping the sponges sense and coordinate various cells in their body when there are no nerves or sensory organs observed. Danielle Ludeman, one of the authors here at the Madreporite, has just published an article describing the sensory organ that she and her coauthors, Nathan Farrar, Ana Riesgo, Jordi Paps, and Sally Leys, discovered in many different species of sponges: primary cilia used to detect changes in water flow. Check out the time-lapse video below to see how responsive sponges are to irritants (in this case sediments) in the water.

Danielle tested if those cilia are used to detect changes in water flow by using drugs that target and knock out the cilia. When the cilia were knocked out or knocked down, the “sneeze” response couldn’t be initiated. If cilia were permitted to grow back following treatment, the “sneeze” response could be initiated. In our kidneys, primary cilia are used to detect water flow. The structure of the paired cilia Danielle found aligns well with those of primary cilia in other animals, further supporting that these are sensory cilia that allow the sponges to detect their environment.

The cilia line the osculum, the chimney-like opening of the sponge. If that osculum is removed, the sponge also is not able to initiate a sneeze response. This led Danielle and co-authors to determine that the osculum can be thought of as a sensory organ, and not just a giant chimney.

The “sneeze” response is shown by an increase in canal diameter followed by a rapid decrease (the black lines in the graphs). Various drugs that affect the cilia also affected that inflation/contraction. Source: Ludeman et al. (2014).

Why does this matter to us, and how does it apply to evolutionary theory? Sponges are one of the earliest branches off of the animal tree of life (the Metazoa). While they are animals, their distant relation to us and to all other animals (collectively called the Eumetazoa) means they diverged from whatever last common ancestor the Metazoa shared and evolved into something quite different and independent of what other animals have evolved into. This isn’t unique–every animal phylum is very different from every other. What is unique is their placement at the base of our collective “family tree.” If a sponge shares a feature that we also have, it’s likely that the proto-animal–the last common ancestor that all animals shared–had that feature as well. It brings us a little bit closer toward understanding how we evolved from single-celled organisms to the multicellular, fantastically complex and coordinated animals we are today.

Still think sponges are boring?(Hint: they are, but only in one way that word is defined!).

The ‘tidal flat’ on the point beside first beach. Does this have a geographical name? Credit: N. Webster

On the same hike with the escaping amphipods, I also saw a tidal flat (is that the right word?) covered in dead things. I’m unsure what the cause of the death was. We were just at the end of a neap tide cycle (with smaller tide fluctuations), and the weather had been really nice (~20C, http://climate.weather.gc.ca/). Perhaps it was just too hot, and this spot was fairly high up on the shore. Perhaps a combination of no really high tides with many hot days was too much. This is unsurprising, and certainly happens all the time. There are many occaisions where you can see swathes of dead barnacles and sea weed after a scorching summer day with a mid-day low tide. This was the first time I saw a diversity of organisms. Beyond fish and chitons (pictured) There were many empty limpet shells and crabs.

We saw this happen several time in just a few minutes, so it must happen constantly. The anemone did react, pulling the amphipod in, but to no avail.

The same amphipod happy on the edge of the anemone. Credit: N. Webster

I can imagine that the anemones do catch and eat one every now and then, but there was no thrashing or panic evident on the part of the amphipod, it simply, carefully, kinda crawled out. It would not be a very viable strategy to swim seemingly randomly around the tide pool without being able to escape small anemones. I think it would be a different story escaping from the larger Anthopleura xanthogrammica.

A view of the full size of the strangely elongated anemone. This might be from growing above some large mussels that have since died. Credit. N. Webster

Another A. elegantissima stretching around a mussel in the same pool. Credit: N. Webster

These anemones also don’t appear typical, they are missing their green colouration, and are strangely elongate. The white colouration is probably bleaching, a loss of the symbiotic zooxanthellae, just like you hear about for coral. There could be several causes, but I think that this loss is due to chemical or temperature stress. The tide pool was fairly high up, and may have been low salinity (based on the algae?)

As we disappeared into the depths of Howe Sound, I peered through the three-inch dome in front of me trying to catch the first glimpse of the sponge reefs below, and my excitement started to grow. But my excitement was not just about getting to see the sponges up close, or about being deeper in the ocean than I have ever been before – although these were both pretty exciting. As we descended into the depths, I realized the opportunity the submarine dive provided to highlight the need to protect the sponge reefs.

When I was first invited to be a passenger in the submarine I was so excited– I was going to be face-to-face with the beautiful glass sponges! (Anyone who knows me will be able to tell you how much I love sponges). And then of course came slight fear – I was going to be face-to-face with the beautiful glass sponges 250 feet (76.2 m) below the surface of the ocean in a submarine! Almost twice the maximum depth for certified, recreational divers.

As we continued our descent down into Howe Sound, I began to make out creamy, white shapes in the water below. I turned to the Hon. Andrew Wilkinson, a Minister in the provincial government, and Jeff Heaton, the pilot of Aquarius, to tell them excitably that there were sponges below! We had descended right down to the sponge reef, and there were the beautiful glass sponges only a few feet from me.

As a graduate student studying sponges I have been involved in research cruises to study the glass sponge reefs. Because the sponge reefs are found so deep in the Strait of Georgia, conventional sampling methods cannot be used. Instead, we use a remotely operated vehicle called ROPOS (picture a very large, square, yellow robot) to sample and survey the reefs, sending live video footage of the reefs up to the research vessel on the surface. I watched this live footage of the glass sponge reefs for hours on a tv screen. Now, I have had the amazing opportunity to experience the sponge reefs with my own eyes.

The glass sponge reefs have given me a sense of awe and wonder ever since I first began my undergraduate studies in Dr. Sally Leys’ lab at the University of Alberta. These glass sponges form massive reefs that serve as crucial habitat for fish, crabs, shrimp and many other critters. The sponges also filter massive amounts of water, removing bacteria and excreting ammonium, a source of nitrogen that can then be used by other animals around the reef.

But sponges are not like any other animal. A sponge is an animal without a digestive system or a nervous system, yet it will respond quickly to something in the water such as sediment, causing it to stop filtering. You wouldn’t know it from looking at the sponge reefs, but sponges are almost constantly pumping water through their bodies. One of the sponge reefs has been estimated to filter over 80,000 L of water every second! And here we have these massive reefs formed from this weird and amazing animal, right on Vancouver’s doorstep.

How have these reefs covered hundreds of square kilometers off the coast of British Columbia and we only just discovered them 25 years ago? How do so few people in Vancouver, in Canada, know that these reefs exist? And how have we, as Canadians, not protected such a beautiful and important habitat?

Protecting the sponge reefs requires public awareness, which is where the submarine dives come in. Until now, most people in Vancouver had never even heard of the sponge reefs. I am very hopeful that the submarine dives will create the public demand for their protection.

Shortly after the submarine dive event I headed down to Fremantle, Australia to attend the World Sponge Conference (yes it exists). While I was there I was talking to an old friend about my research. Their response was “Oh! I heard about sponges recently. It was about some sponge reefs that are only found in Canada. Is that what you study?” And so the ripples spread.

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Disclaimer

This is an unofficial blog with contributions from graduate students, researchers, and students studying at Bamfield Marine Sciences Centre. The information in the blog is that of the individual writers and does not represent the opinions of the marine sciences centre.